The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An eco-friendly vehicle such as an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, and a fuel cell vehicle is driven using electric energy stored in a high-voltage main battery. The eco-friendly vehicle includes a low-voltage DC-DC converter (LDC) for converting high-voltage power output from a main battery into a low voltage in order to supply a power voltage to a low-voltage electric load driven with a low voltage.
In general, an LDC uses a field effect transistor (FET) as a switching device, on/off of which is controlled by PWM. In this regard, as gate resistance of an FET to which a PWM signal for controlling on/off of the FET is applied is reduced, switching loss is reduced. A method of reducing gate resistance of FET based on this characteristic is one method for enhancing efficiency of an LDC.
However, the method of reducing gate resistance has caused such that an LDC has difficulty in operating as a heavy load. This is because, when a small-size gate resistor is used, a voltage between a drain and a source of an FET is increased toward a high load and, accordingly, the FET may be damaged.
When a size of gate resistance is set during LDC design, an efficiency curve according to load may not be changed during driving. That is, a conventional LDC has a difficulty in reflecting an efficiency curve optimized according to a driver load pattern.